Russia launched 25 Iranian kamikaze drones on the southern parts of the Odesa region on Sunday, where Ukraine has its crucial grain export Danube ports.
The Danube has become Ukraine's main route for exporting grain since July, when Russia quit a UN and Turkey-brokered deal that had given safe passage to Kyiv's exports of grains, oilseeds and vegetables oils via the Black Sea.
Sunday's attack took place the day before Russian President Vladimir Putin and his Turkish counterpart Tayyip Erdogan are due to hold talks in the Russian Black Sea resort of Sochi. Turkey has been pressing to revive the grain deal.
Ukraine's South Military Command said on social media that at least two civilians were injured in the early morning attack on what it called "civil infrastructure of the Danube".
The Ukrainian Air Force said air defence systems shot down 22 of the 25 Iranian-made Shahed drones launched by Russia.
Iran has been supplying hundreds of its Shahed drones to Russia since mid-2022 but denies there were delivered to be used for attacks on Ukraine. The Western alliance supporting Ukraine has imposed sanctions on individuals and companies involved in supplying the drones.
The military said a fire that resulted from the attack at one facility was quickly extinguished.
The Russian Defense Ministry was quoted by Interfax as saying that a group of Russian drones successfully struck fuel depots at the Reni port used by the Ukrainian military.
"Russian terrorists continue to attack port infrastructure in the hope of provoking a food crisis and famine in the world," the Ukrainian president's chief of staff Andriy Yermak wrote on Telegram.